DE10392783B4 - Device for molding molten materials - Google Patents

Abstract

cast device for processing metal material in molten or semi-solid Condition comprising a container (12), a body that inside a chamber defines an inlet (18) in conjunction with the chamber to allow the supply of material into the chamber and an outlet (20) in communication with the chamber for discharging to allow material from the chamber, wherein the body Furthermore a sidewall portion having an outer layer (62) of a first one Material, an inner layer (66) of a second material, the defines an inside of the chamber, and an intermediate layer (64) of a third material between the outer layer (62) and the inner layer (66), wherein the first material is Ni-based Composition with more than 10% Cr in weight%, more than 7.5% Co, more than 2.5% Mo, in the range of 0-6% W, less than 4% Nb, more than 2% Al, more than 2.4% Ti and more than ...

Description

BACKGROUND THE INVENTION

AREA OF INVENTION

The The present invention relates to a container for producing molten Materials. In particular, the present invention relates to a Container, the for The handling of the process environment is optimized during manufacture of molten or liquid Metals is found, and their forms in manufacturing objects.

metal compositions with dendritic structures at ambient temperatures are conventional melted and then subjected to high pressure die casting procedures Service. This conventional Die casting procedures are limited in that they include porosity, enamel loss, Contamination, excessive waste, a high energy consumption, long lasting power cycles, one limited form life and limited shape configurations. conventional processes promote Furthermore the formation of a variety of microstructural defects, such as about porosity, which then a secondary Processing of the objects require and as well for using conservative construction techniques with reference lead to their mechanical properties.

It are known processes for the formation of metal compositions, whose Microstructures when in a semi-solid state from rounded or spherical Degenerate dendritic particles consist of a continuous liquid Phase are surrounded. This is in contrast to the classical equilibrium microstructure of dendrites surrounded by a continuous liquid phase. These New structures show non-Newtonian viscosity, a inverse relationship between the viscosity and the shear rate. The materials themselves are known in this state as thixotropic materials.

One Process for converting a dendritic composition into Thixotropic material provides heating of the material composition or alloy (hereinafter referred to simply as "alloy"), to a temperature above its liquidus temperature, whereupon the liquid alloy is subjected to a shear or stir when subjected to the range of two-phase equilibrium chilled becomes. A consequence of sufficient stirring or back and forth during of cooling is that the initial solidified phases of the alloy form a nucleus of crystallization and as rounded primary particles grow (as opposed to interconnected dendritic particles). These primary solids consist of discrete degenerate dendritic beads and are of a matrix of an unconsolidated section of the liquid Surrounded metal or alloy.

One another method for forming thixotropic materials sees this Heat the alloy to a temperature at which a part, however not the entire alloy is in a liquid state. The alloy can then be touched or to be moved back and forth. The stirring sets all dendritic particles in degenerated dendritic beads around. In this method, it is preferable that when with the stir is begun, the semi-solid metal contains more liquid than solid phase.

An injection molding technique using thixotropic alloys to provide a "quasi-cast" state is also known. With this technique, the feed material is fed into a container in which it is additionally heated and at least partially melted. Next, the alloy is mechanically reciprocated by the action of a rotary screw, rotating plates, or other means. When the material is processed, it is fed into the container. The combination of partial melting and simultaneous agitation produces a slurry of the alloy containing discrete degenerate dendritic spherical particles or, in other words, a semi-solid state of material having thixotropic properties. The thixotropic slurry is transferred to another zone, which may be a second container located adjacent a nozzle. The slurry can be prevented from leaching or dripping from the nozzle tip by controlled solidification of a solid metal plug from the material in the nozzle (by controlling the nozzle temperature). Alternatively, a mechanical or other sealing scheme may be used. The sealed nozzle provides protection to the slurry from oxidation or from formation of oxide on the inner wall of the nozzle, otherwise into the finished molded part would be registered. The sealed nozzle also seals the die-casting cavity on the injection side, possibly facilitating the use of negative pressure to evacuate the die-cast cavity, resulting in an increase in the complexity and quality of the parts so formed.

As soon as a suitable amount of slurry for the Production of the item in this zone a piston, a worm, or some other mechanism is the material to be injected into the die-casting cavity that has the desired Solid article forms. Such casting or injection machines of the above mentioned or related varieties are presently known as semi-solid metal spraying (SSMI) molding machines designated.

Current to lead SSMI molding machines typically form part of the heating of the Material in a boiler of the machine. The material will fed to a portion of the boiler, while this reduced to Temperature, and then to a series of heating zones advanced, the temperature of the material quickly and at least initially progressively increased becomes. The heating elements themselves, typically resistance or Induction heaters, which may or may not be zones along the boiler can not progressively hotter be as the previous heating elements. This exists thermal gradient both by the thickness of the boiler as along the length of the Boiler.

A Boiler construction for Such machines provides that the boiler as long (up to to 27.94 cm) and thick (outside diameter up to 27,94 cm with 7,62 to 10,16 cm thick walls) monolithic cylinders are formed. Because the size and the Throughput capacity These machines have increased the length and thicknesses of the boiler increased accordingly. This has increased thermal gradients over the led whole boiler and unforeseen and unexpected consequences. The primary Boiler material, wrought alloy 718 (with a limiting composition of: nickel (plus cobalt) 50.00-55.00%; Chrome 17.00-21.00%; Iron as the remainder; Colombium (plus tantalum) 4.75-5.50%; Molybdenum 2.80-3.30%; Titanium 0.65-1.15%; Aluminum 0.20-0.80%; Cobalt max. 1.00%; Carbon max. 0.08%; Manganese max. 0.35%; silicon Max. 0.35%; Phosphorus max. 0.015%; Sulfur max. 0.015%; Boron max. 0.006%; Copper max. 0.30%) used to create these cauldrons was, is often expensive and hard to get. Furthermore shows alloy 718 unfavorable Stress cracking properties, insufficient elongation property and phase instability.

Fine grained alloy 718 big quality is expensive and exclusive available as a cast / kneaded blank, which means extensive drilling and external machining requires to complex boiler to shape. The ablation on alloy 718, which occurs when this route is committed amounts to up to 50%. Furthermore Alloy 718 is unstable at 600-700 ° C and tends to have its double-coated fine gamma hardening phase in a fragile Transform delta phase. Impact energy (Charpy V-notch) and Stress resistance can thereby impaired be.

Walzing (hipping, hereafter called hipping) of complex raw Alloy 718 forms is desirable to increase yield and apply liners. However, cast / kneaded alloy 718 suffers from grain growth into large grains of ASTM No. 00. Impact energy (Charpy V-notch) and stress rupture strength may again be compromised. A powder metal alloy 718 maintains a finer grain size during hipping; however, the stress rupture properties (life and ductility) continue to suffer seriously. Furthermore, thixomolding ^® expanded, a semi-solid thixotropic metal injection molding alloys, high temperature alloys, which confers the alloy 718 additional instability.

In some cases fractured monolithic kettles have been analyzed and It was found that the boiler as a result of thermal stress had broken and in particular as a result of thermal shock in the cold or input end of the boiler. The cold or entrance end a boiler referred to in this section or that End at which the material first in the container or boiler passes. Exactly in this section most occur intense thermal gradients, in particular in an intermediate temperature range of the cold section, the downstream from the point where the material enters. Great grained alloy 718 is especially vulnerable for cracking underneath these high voltage conditions.

During use of an SSMI molding machine, the solid starting material, which may be in pellet or chip form, may be fed into the vessel at ambient temperatures, approximately at 75 ° F. Being long and thick, the boilers of these molding machines are inherently thermally inefficient for heating a material fed into them. Due to the inflow of "cold" starting material, a Be rich of the boiler cooled significantly on its inside. However, the outside of this area is not appreciably affected or cooled by the starting material due to the positioning of the heaters around this area. A significant thermal gradient, measured across the thickness of the boiler, is thereby induced in this area of the boiler. A thermal gradient is also induced along the kettle length. In the area of the boiler where it has been determined that the highest thermal gradient is developing, the boiler is heated more intensely due to the less frequent "switching off" of the heaters.

Within of the boiler leads Shearing action on and movement of the starting material in the longitudinal direction the different heating zones of the boiler cause the temperature of the starting material increases, leaving a balance on one desired Level takes place when it is the opposite or hot end reached the boiler. On the hot At the end of the boiler, the processed material usually shows temperatures in the range of 1050-1100 ° F depending on the special processed alloy. For processing magnesium are the maximum temperatures to which the inner sections are subjected to the boiler, about 1180 ° F. The exterior of the boiler can go all the way to 1530 ° F heated to achieve these temperatures.

If the starting material is heated the inside of the boiler will see an increase in theirs accordingly Temperature. This increase the inside temperatures will go down to a certain extent the entire length of the boiler, including the section caused by the inflow of cold material chilled becomes, at which the extent diminishes is.

As soon as a sufficient amount of material has accumulated and the material shows its thixotropic properties, the material is in the Cast cavity injected, which forms a shape in accordance with the mold of the desired having to be manufactured article. Additional starting material is then or continuously into the cold section of the boiler initiated, which in turn the temperature of the boiler inside is lowered.

As the above Discussion demonstrates, suffers the inside of the boiler, in particular in the area of the boiler into which the starting material is fed, a cycle of its temperature during operation of the SSMI molding machine. This thermal gradient between the inside and outside The boiler was considered to be up to 350 ° C determined.

There the nickel content of the alloy 718 is subject to corrosion molten magnesium, which is currently the farthest commonly used thixotropic material, the containers are for Preparation of thixotropic alloy lined with a Sleeve off magnesiumbeständigem Material. Several such known materials are Stellite 12 (nominally 30 Cr, 8.3 W and 1.4 C, Stoody Doloro-Stellite Corp.), PM 0.80 alloy (nominal 0.8 C, 27.81 Cr, 4.11 W, balance Co with 0.66N) and Nb-based alloys (such as Nb-30Ti-20W). Further Molten materials such as aluminum are also high grade corrosive and erosive for Materials conventionally for ingredients the machines for the formation of thixotropic materials or otherwise Processing of these alloys are used.

In the case in which liners are used must be obvious the expansion coefficients of the container and the lining with each other be compatible for the machine to work. A problem with lined containers concerns the delamination or detachment of the lining from the rest of the container or the shell. An analysis of heavily loaded boilers has revealed that a gap between the lining and the shell occurs. This Gap on his part leads to a reduction in heat transfer efficiency between the lining and the shell, which requires that yet higher temperatures be applied to the shell, creating greater thermal gradients throughout the container become.

On Reason for the significant oscillation of the thermal gradient in the container suffers the container thermal fatigue and Shock. This can lead to cracking in the container and lead the lining. As soon as in the container liner Cracks may occur, processed alloy in the lining penetrate and the container attack. Both the cracking of the lining as attacking of the container the alloy has been proven to be early Failure of the boiler out.

In response to the above-listed and other disadvantages, a multi-part boiler construction has been provided wherein one portion of the boiler for the preparation of the thixotropic material and the other portion of the boiler are designed for the requirements of high pressure forming. These sections are called cold and hot outlet sections of the boiler and they are different Licher way constructed and interconnected.

In a multi-part construction is the cold section with a relatively thin Material section created (which with a low accompanied). This material, which can also be cheaper than the material of the hot Section, shows improved thermal conductivity and has a reduced coefficient of thermal expansion relative to the material of the hot Section. This material also shows good wear and corrosion resistance across from the thixotropic material to be processed. Several preferred Materials for The cold section of the boiler are 422 stainless steel, T-2888 alloy and alloy 909, which may be lined with a Nb-based Alloy (such as Nb-30Ti-20W).

Of the name is Section is made of a relatively thick (and thus highly stress-resistant) wärmeermüdungsbeständigem, creep resistant and heat shock resistant material created. A configuration of the hot section sees the use of fine-grained Alloy 718 with a hipped lining of one Nb-based alloy, such as Nb-30Ti-20W, in favor of lower cost and better attack resistance in relation to the material to be processed.

One nozzle section (the one with the end of the hot Section opposite connected to the cold section) can be created in a similar way So that residual material in the nozzle can be solidified in a sealing plug. Otherwise can the nozzle be provided with a mechanical sealing mechanism.

From the American patents US 5,819,839 and US 5,711,366 For example, a casting chamber for thixocasting is known, in which an outer layer is a corrosion-resistant Nb-based layer to which an inner layer is followed by another material, optionally with an intermediate layer of a third material.

While that Problem big thermal gradient in a container above for some particular machines and containers for semi-solid metal injection molding have been explained is, the problem becomes large thermal gradients in a melting or pressure vessel in a big one Variety of metal forming processes and devices encountered. While the known boiler or other container designs for their work adequately, there is still one Need for an improved container construction, the thermal stresses minimized and provides a long life under higher operating temperatures.

SHORT SUMMARY THE INVENTION

A Main object of the present invention is the above meet these needs by providing an improved container construction for preparing molten or semi-molten metals, including, but not limited thereto Magnesium and aluminum.

A The object of the present invention is a construction with reduced thermal stresses among the above mentioned higher ones To create operating conditions.

A Another object of the present invention is a construction to create a higher one Lifespan even under elevated Operating temperatures possible.

A Another object of this invention is a construction with reduced static and cyclic thermal stresses.

Yet Another object of this invention is to provide a construction to create low cost and high production rates.

A Another object of this invention is to provide one-step hipping to create pure mold components or Nutzformkomponenten, which is characterized by a good load time, good ductility and good corrosion resistance across from liquid Distinguish metals and air.

Yet Another object of the present invention is to provide Shell of the alloy 718 boiler by a more stable, oxidation resistant, ductile fine-grained Alloy 720 or an alloy of similar composition to replace.

to solution one or the other or all In the foregoing, the present invention provides a container for processing of metal material in molten or semi-molten state ready. The container in turn comprises a body which defines a chamber in which the material is taken up. To accommodate the material, an inlet is also defined in this body. Besides that is for discharging the material from the chamber and out of the body Outlet in the body established. The body is further made of a side wall portion, which consists of three Layers is formed, an outer layer, an inner layer and an intermediate layer.

The outer layer is made of a first material, the inner layer is made of formed of a different material from the first material. Furthermore The inner layer defines the inside of the aforementioned chamber firmly. Located between the inner and outer layers is located the intermediate layer. This layer is from one of both of the first as formed by the second material different third material. The material of the intermediate layer is softer than the material of both the outer layer as the inner layer and thereby minimizes the thermal gradient, the through the thickness of the container as well as along the length of the container occurs. This layer is with the inner and outer layers connected and blocked any liquid metal corrosion attack the outer layer. By reducing the thermal gradient loads or stresses in the container are also reduced and This results in a corresponding increase in the service life of the container.

A Modification of the curing mechanism for the Alloy 718 is suitable for stabilizing the curing mechanism and the delta phase precipitation to prevent. This provides Ni-based Superalloys with greater strength at 600-750 ° C at long Lifespan and retention of ductility. These alloys, for example Alloy 720, use lower Nb and higher Ti + Al to achieve a stable gamma prime phase. These preferred alloys can at high temperatures (eg 1150 ° C) without pronounced grain growth that found in the cast / kneaded alloy 718 will, and without interference the properties encountered in powder metallurgy alloy 718 is, starting from grain boundary precipitates. This allows three-layer constructions of the superalloy boiler, a tie-layer and a liner be taken one step to make pure shapes, the little machining and material loss with it bring and therefore more cost-effective are.

Inserts for hot runners and hot spouts as well Shot bushes can be created in the same three-layer format.

Further Advantages and further benefits of the present invention are apparent those skilled in the art to which the present Invention, from the following description of the preferred embodiment and the appended claims in conjunction with the attached drawings.

SHORT DESCRIPTION THE DRAWINGS

1 Figure 9 is a general view of an apparatus having a portion of a container in accordance with the present invention utilized to convert feedstock to a molten and / or semi-molten state; and

2 Figure 11 is an enlarged view of a portion of a three-layer construction container in accordance with the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings, a metal material processing apparatus is in a thixotropic state and molded material for molded, cast or forged articles constructed in accordance with the present invention is shown in FIG 1 generally shown and with the reference numeral 10 designated. Unlike typical casting and forging machines is the present invention provides for the use of a solid starting material of metal or metal alloy (hereinafter referred to as "alloy" for simplicity). This eliminates the need for a melting furnace in die casting or forging.

While in 1 in connection with the device 10 11, it will be noted that the container construction detailed below is also applicable to the melting vessels of other machines used to melt metals. The present invention is therefore not to be construed as limited to a particular machine construction, a specific process for melting metal and alloys, or for use in melting only certain metals or alloys.

The device 10 , in the 1 Generally, a container or kettle or shot sleeve is included 12 , the one or the one with a form 16 connected is. As explained in more detail below, the container contains 12 an inlet section 14 , a shot section 15 and an outlet nozzle 30 , An inlet 18 is in the inlet section 14 arranged and an outlet 20 is in the shot section 15 arranged. The inlet 18 is designed to charge the alloy raw material (shown in phantom lines) in solid particulate, palletized, or chip form from a feed hopper 22 to receive, in which the starting material can be preheated.

It is anticipated that in the device 10 formed articles show a significantly lower defect rate and lower porosity than non-thixotropic shaped or conventionally die cast articles. It is known that by reducing the porosity, the strength and ductility of the article can be increased. Any reduction in casting defects as well as any reduction in porosity is obviously desirable.

A group of alloys suitable for processing in the device 10 include magnesium alloys and Al, Zn, Ti and Cu alloys. However, the present invention should not be construed as being limited thereto, since it is believed that any metal or metal alloy capable of being processed in semi-solid or liquid state is usable with the present invention.

At the bottom or at the bottom of the feed hopper 22 The raw material is passed through an outlet 32 in a volumetric feeder or feed cylinder 38 discharged. A feed screw (not shown) is in the feeder 38 arranged and is by a suitable drive mechanism 40 , such as an electric motor, rotationally driven. The rotation of the screw inside the feeder 38 pushes the raw material at a predetermined rate for feeding into the keg 12 through a transfer line or a feed throat 42 and the inlet 18 to. Other mechanisms for providing the raw material to the inlet 18 can be used alternatively.

Once in the container 12 is received, heating heating elements 24 the raw material to a predetermined temperature, so that the metal is brought into its two-phase range. In this two-phase region, the temperature of the raw material is in the container 12 between the solidus and liquidus temperatures of the alloy, it partially melts and is in an equilibrium state containing both solid and liquid phases.

The temperature control can work with different types of heating or cooling elements 24 be provided to achieve its intended purpose. Heating / cooling elements 24 are in 1 shown representatively. Induction heating coils or band resistance heaters are preferably used.

A temperature control in the form of band heaters 24 is further disposed around the nozzle to assist in controlling its temperature and to permit the formation of a critically sized solid alloy plug. The plug prevents the alloy from dripping or the backflow of air (oxygen) or contaminants into the internal protective atmosphere (typically argon) of the device 10 , Such a plug facilitates the evacuation of the mold 16 or emptying this mold, if desired, for example for vacuum assisted molding. Alternatively to the formation of a plug mechanical seal mechanisms such as sliders or other valves may be used.

The apparatus may also include a stationary platen and a movable platen, each having a stationary mold half 16 and a movable mold half are mounted. The mold halves around grasp insides, which in combination form a cavity 100 in the form of the object to be molded. The mold cavity 100 is with the nozzle 30 connected via a spout, a gate and a pouring channel, which is generally with 102 are designated. The actuation of the mold 16 Incidentally, it is of conventional type and is therefore not explained in detail here.

A back and forth running snail 26 is in the container 12 arranged and rotated in a similar manner to the drill which is in the feeder 38 is arranged, by a suitable drive mechanism 44 , such as by an electric motor, so that wings 28 on the snail 26 Exert shear forces on the alloy and the alloy through the container 12 towards the outlet 20 move. The shearing action conditions the alloy into a thixotropic slurry consisting of globules of rounded degenerate dendritic structures surrounded by a liquid phase. As an alternative to the snail 26 For example, other mechanisms or means may be used to agitate and / or stir the feedstock through the container 12 to move. Various types of rotating plates as well as gravity can perform these functions.

During operation of the device 10 become the heaters 24 turned on to the container 12 carefully heat to a desired temperature profile over its length. Typically, a high temperature profile is required to form thin section parts, a moderate temperature profile is desired for forming mixed parts of thin and thick cross sections, and a low temperature profile is desired for forming thick section parts. Once a thorough warm-up is achieved, the system controller operates 34 the drive mechanism 40 of the feeder 38 and causes the screw in the feeder 38 to turn. This screw conveys the starting material from the feed hopper 22 to the feed throat 42 and in the container 12 into through its inlet 18 , If desired, preheating the starting material is carried out in either the feed hopper 22 , the feeder 38 or the feed throat 42 , as explained in more detail below.

In the container 12 the feedstock gets through the rotating screw 26 engaged by the drive mechanism 44 in turn, in turn, through the controller 34 is pressed. Inside the hole 46 of the container 12 the starting material is conveyed and subjected to shearing forces by the wings 28 on the snail 26 , If the starting material is the container 12 passes through, heat is through the heater 24 and the shear increases the temperature of the feedstock to the desired temperature between its solidus and liquidus temperatures. In this temperature range, the solid starting material is transformed into a semi-solid state consisting of the liquid phase of some of its constituents, in which a solid phase of the remainder of its constituents is located. The rotation or rotation of the screw 26 and the wing 28 continues to initiate into the semi-solid alloy at a rate of shear sufficient to inhibit dendritic growth relative to the solid particles, thereby producing a thixotropic slurry.

The slurry is passed through the container 12 Advances until a suitable amount of the slurry in the front section 21 (the accumulation area) of the container 12 has accumulated. The screw rotation is controlled by the controller 34 interrupted, who then an actuator 36 signals the snail 26 advance and the alloy through a nozzle 30 to crowd with the outlet 20 connected, and in the form 16 into it. The snail 26 is initially accelerated to a speed of about 2.54 to 12.7 cm / second. A check valve (not shown) prevents material from moving rearward toward the inlet 18 while advancing the screw 26 flows. This leads to a compaction of the hot batch in the front section 21 of the container 12 ,

For the nozzle 30 itself, construction materials are alloy steel (such as T-2888), PM 0.8C alloys, and Nb-based alloys such as Nb-30Ti-20W. In a preferred construction, the nozzle is 30 monolithic formed from one of the abovementioned alloys. In a further preferred embodiment, the nozzle is 30 formed from an alloy 720 and tilted to provide it with a resistant inner surface of Nb-based alloy or PM 0.8C alloy.

How out 2 shows, the inlet section stands 14 of the container 12 fitting in engagement with the weft section 15 , making a continuous hole 46 cooperative with the insides 48 . 50 of the inlet section 14 and the weft section 15 is fixed. To the two container sections 14 . 15 determine is the shot section 15 with a radial flange 52 provided in the mounting holes 54 are fixed. Corresponding threaded holes are in the fitting section 58 of the container shot section 15 established. Threaded fasteners 60 passing through the holes 54 in the flange 52 are engaged, are in threaded engagement with the threaded holes 56 and thereby lay the sections 14 . 15 stuck together. Obviously, a one-piece container may be used instead of the two-part container 23 used as in 1 as well as its entire length in accordance with the present invention, as explained in more detail below.

The container construction according to the present invention overcomes the disadvantages of the prior art by minimizing the thermal gradient experienced across its thickness and along its length. In particular with reference to 2 includes the container according to the invention 12 three layers, the outer layer or shell or shell 62 , Intermediate layer 64 and lining or inner layer 66 be designated. As in 2 shown is the intermediate layer 64 between the outer layer 62 and the inner layer 66 arranged. As explained below, the presence of the intermediate layer minimizes 64 the radial heat gradient through the thickness or wall thickness of the container 12 ,

The intermediate layer 64 in particular is relatively softer than both the outer layer 62 as well as the inner layer 66 , The intermediate layer 64 prefers to connect, but this does not have to do the outer layer 62 of the container 12 with the inner layer 66 , and when they are connected, is the interlayer 64 preferably with the outer layer and the inner layer 66 by hot isostatic pressing (hipping). In addition, the presence of an intermediate layer prevents 64 a delamination of the outer layer 62 from the inner layer 66 , whereby the overall stability of the container construction is increased.

B. Flutzuführung ΔT = 273°F

In a preferred embodiment of this invention, the intermediate layer is 64 formed from an alloy of low carbon iron. Alternatively, other materials may be used that are compatible with the outer layer 62 or the inner layer 66 do not form a brittle layer. Likewise preferred is that the intermediate layer 64 is corrosion resistant to Al, Mg or Zn. In order to improve the service life of the container construction, the preferred thickness of the intermediate layer is 64 in the range of 0.127 cm to 0.381 cm, and more preferably in the range of 1.524 to 0.3048 cm. Table I shows the effect of the intermediate layer 64 on the tension or strain that the container 12 suffers. Table I Outer Layer (Alloy 720) Inner Layer (T-20), A. as prepared

B. Surface supply ΔT = 273 ° F

Table I shows that the presence of the intermediate layer 64 the tension on both the inner layer 66 like the outer layer 62 reduced both during manufacture and operation. Table II additionally shows the effect of the intermediate layer 64 to tension using a container with a 4,699 cm thick fluted 720 outer layer at 0,508 cm thick stellite inner layer. The values in the table were measured at a full start with ΔT = 403 ° F. Table II

The outer layer 62 forms the furthest outermost layer of the container 12 , The presence of the intermediate layer is preferred 64 it allows the material used in the outer layer construction to be replaced by material having the following properties: reduced grain size after hipping; improved stress cracking properties; no softening or brittleness by precipitation of a brittle delta phase; a low heat coefficient; an increased resistance to oxidation and oxidation accelerated fatigue. A preferred material having the above properties is fine-grained alloy 720. Alloy similar to alloy 720, such as alloy 718 and alloy 720 are listed in Table III. Table III Comparison of Properties of Alloy 718 with Other Superalloys, Such as 720

The above Table III shows the superior Properties of the superalloy 720 compared to the alloy 718 and other alloys generally similar to the alloy 720 on. Alternatively you can other alloys are used which have similar compositions and Show properties. Typically, the composition range is of these preferred superalloys> 10% Cr,> 7.5% Co,> 2.5% Mo, 0-6% W, <4% Nb,> 2% Al,> 2.4% Ti,> 5.5% Al + Ti. Additionally the ultimate tensile strength (UTS) at 1200 ° F is preferably greater than 180 ksi and at 1400 ° F greater than 150 ksi. In similar Way is the yield strength (YS) at 1200 ° F preferably greater than 140 ksi and at 1400 ° F greater than 130 ksi. The stress cracking resistance for 1000 hours at 1200 ° F is greater than 100 ksi and at 1400 ° F greater than 60 ksi. The preferred alloy 720 shows reduced grain size Hipping, a stress crack life at 1200 ° F of 430 hours at gradual Load of 100 to 130 ksi and 23% elongation. In addition, the alloy is subject 720 no softening or brittle in delta precipitation in 50000 hours at 1400 ° F and she owns as well a smaller heat coefficient (CTE) of 13.7. The alloy 720 also shows superior oxidation resistance and durability across from oxidation-accelerated fatigue at 1200 ° F by reducing the Nb content and increasing the Al content.

B. Spannungsrisseigenschaften bei 1200°F

Tabelle V

• *Nach 5000 Stunden bei 1300°F bzw. einem Jahr Betrieb

Table IV shows the creep properties and stress cracking properties of alloys 718 and 720 at 1200 ° F. As can be seen from this table, the 720 alloy exhibits higher creep resistance and better strength than the 718 alloy. In addition, Table V compares the brittleness of the unstable 718 alloy with the stable low Nb Waspaloy during 5000 hours of simulated operation, where "RA" for the area reduction is and where "CVN" stands for Charpy V-Notch toughness. As shown in Table V, the container has 12 using waspaloy negligible CVN loss. On the other hand, the alloy 718 shows a sharp CVN loss, which increases the life of the container 12 reduced. Table IV A. Creep Properties

B. Stress cracking properties at 1200 ° F

Table V

• * After 5000 hours at 1300 ° F or one year of operation

The presence of the intermediate layer 64 it also allows the outer layer thickness to be reduced, thereby improving heat transfer, reducing stress, and increasing the thermal gradient across the container 12 is reduced. Without the present invention, the thickness of the outer layer would 62 typically ranging from 4,699 cm to 9,34212 cm.

Under Use of the present invention is the use of an outer layer thickness less than 4,699 cm possible. It is anticipated that the outer layer thicknesses will be under use of the invention range from 2.54 to less than 4.699 cm, and preferably in the range of 3.175 to 4.445 cm.

Table VI shows the effect of the thickness of the outer layer 62 on the tension on the container 12 , For the data listed in Table VI, the materials used are in the outer layer 62 , the intermediate layer 64 and the inner layer 66 each alloy HIP 720 for the outer layer 62, 0.508 cm, T-20 for the inner layer 66 and 0.1524 cm, iron for the intermediate layer 64 , Table VI Flood Feed

Using the intermediate layer explained above 64 are changes in the composition of the inner layer 66 and their construction possible. In particular, usable are a break-melting alloy for the inner layer 66 based on high peritectic temperature alloying elements or melting points in the binary phase diagrams. Such highly refractory metal and elements have the following characteristics: a small coefficient of expansion (and resulting reductions in stress both in the inner layer 66 as in the outer layer); a small elastic modulus (E); high thermal conductivity; good corrosion resistance against material to be processed; and improved strength, toughness and hardness.

The material according to the invention for the inner layer 66 In particular, when Mg, Al or Zn is processed, it is an Nb alloy, especially T-20, T-22 and T-23-Nb alloys. Due to the intermediate layer 64 can change the thickness of the inner layer 66 be significantly reduced starting from a currently used thickness of 1.27 cm and larger. With the present invention, the inner layer thickness can be reduced below 1.27 cm. For practical reasons, it is believed that the lower limit on the inner layer thickness is about 0.381 cm, although smaller thicknesses may be possible. Preferably, the inner layer thickness range is about 0.381 cm to less than 1.27 cm, and more preferably, the inner layer thickness is in the range of 0.381 cm to 0.635 cm.

Table VII shows the effect of the inner layer composition of the above-mentioned Nb alloy compositions on thermal shock (TS) and combined stresses. Table VII

B. Außenschicht, 4,699 cm und Legierung 718; Vollleistungsstart bei ΔT = 403°F

Table VIII shows the effect on the effect of the inner layer material on the stresses. The first part of the table shows the voltage value during the flood supply at ΔT = 273 ° F and the second part of the table concerns the initial full power start at ΔT 403 ° F. Table VIII A. Outer layer, 4.699 cm and alloy 718; Surface supply at ΔT = 273 ° F

Outer layer, 4.699 cm and Alloy 718; Full power start at ΔT = 403 ° F

As can be seen from the above tables, the use of the intermediate layer reduces 64 the tension on the outer layer 62 or the inner layer 66 , At its core, the intermediate layer works 64 as a buffer zone, causing premature cracking of the outer layer 62 is avoided.

The inner layer thickness also has an effect on the tension and Table IX shows this effect for a T-20 inner layer 66 , As in the above tables, the outer layer is made 62 made of alloy 720 and she is 4,699 inches thick; the inner layer 60 consists of T-20 alloy and the operating conditions are flood supply at ΔT = 273 ° F. Table IX

The thicknesses for the inner layer 66 can be increased to values over 0.508 cm; however, such increases result in an increase in the overall cost of the container 12 and actually result in a sacrifice of strength for the container 12 , From the foregoing it can be seen that the present invention offers numerous advantages and benefits in the construction of containers for melting metals and alloys. While the foregoing discussion relates to the preferred embodiment of the invention, it is to be understood that the invention is susceptible to modification, variation and alteration without departing from the scope of the protection as defined by the appended claims.

Claims (25)

Casting apparatus for processing metal material in a molten or semi-solid state, comprising a container ( 12 ), a body which defines a chamber inside, an inlet ( 18 ) in conjunction with the chamber to allow the supply of material into the chamber, and an outlet ( 20 ) in conjunction with the chamber to allow the discharge of material from the chamber, the body further comprising a sidewall portion having an outer layer (US Pat. 62 ) of a first material, an inner layer ( 66 ) of a second material, which defines an inner side of the chamber, and an intermediate layer ( 64 ) of a third material which is between the outer layer ( 62 ) and the inner layer ( 66 wherein the first material is a Ni-based composition having in wt% more than 10% Cr, more than 7.5% Co, more than 2.5% Mo, in the range of 0-6% W, less than 4% Nb, more than 2% Al, more than 2.4% Ti, and more than 5.5% Al + Ti, wherein the second material is an Nb alloy, and wherein the third material is iron or is a low carbon iron alloy. Device according to claim 1, characterized in that that the third material softer than the first and second materials is. Device according to claim 1, characterized in that the intermediate layer ( 64 ) the outer layer ( 62 ) with the inner layer ( 66 ) connects. Device according to claim 1, characterized in that the intermediate layer ( 64 ) has a thickness of less than 0.508 cm. Device according to claim 1, characterized in that the intermediate layer ( 64 ) has a thickness of less than 0.254 cm. Device according to claim 1, characterized in that the intermediate layer ( 64 ) has a thickness of about 0.1524 cm. Device according to claim 1, characterized in that the intermediate layer ( 64 ) Iron with clot is carbon content. Device according to claim 1, characterized in that the second material is selected from the group consisting of an Nb alloy T-20, T-22 or T-23. Device according to claim 1, characterized in that the inner layer ( 66 ) has a thickness less than 1.27 cm. Device according to claim 1, characterized in that the inner layer ( 66 ) has a thickness less than 0.635 cm. Device according to claim 1, characterized in that the inner layer ( 66 ) has a thickness less than 0.381 cm. Device according to claim 1, characterized in that the outer layer ( 62 ) has a thickness of less than 4.445 cm. Device according to claim 1, characterized in that the outer layer ( 62 ) has a thickness of less than 3.175 cm. Device according to claim 1, characterized in that that the first material is a hopped material. Device according to claim 1, characterized in that that the second material is a hopped material. Device according to claim 1, characterized in that that the third material is a hopped material. Device according to claim 1, characterized in that that the first material, the second material and the third material all are hipped materials. Device according to claim 1, characterized in that that the first material, the second material and the third material Tipped materials are formed in a one-step process are. The apparatus of claim 1, further comprising: a feeder ( 38 ) connected to the container ( 12 ) is connected to the material there through the inlet ( 18 ); a movement device for moving the material through the container ( 12 ); and a discharge device for discharging the material from the outlet ( 20 ) of the container ( 12 ) in molten or semi-molten state. Device according to claim 1, characterized in that the intermediate layer ( 64 ) is more ductile than the first material and the second material. Apparatus according to claim 1, further comprising a shear force applying means, which is disposed in the chamber, wherein the shear force applying means induced in the material shearing force sufficient dendritic To prevent growth in the materials. Apparatus according to claim 21, characterized in that the shear force applying means a screw ( 26 ). Apparatus according to claim 21, characterized in that the movement means a screw ( 26 ). Apparatus according to claim 21, characterized in that the discharge device is a longitudinally movable element contains. Apparatus according to claim 24, characterized in that the discharge device a reciprocating screw ( 26 ) contains.